How to write this Flutter code more efficiently? - flutter

Question

As you can see in first part I'm checking that a certain value contains in a document from Firestore and returns a boolean value. Now I'm calling that function in a build and based on that return value I'm changing a chip color (second part).
Now the problem is maybe because I'm calling it in a build function so its being called continuously and on that build and it costing me a ton of reads in Firestore or maybe the function is inefficient. How can I write this more efficiently?
checkAtt(String name, id , date) async{
var ref = _db.collection('subjects').document(id).collection('Att').document(date);
var docref = await ref.get();
return docref.data.containsKey(name)
?true
:false;
}
class PresentChip extends StatefulWidget {
final candidate;
PresentChip(
this.candidate, {
Key key,
}) : super(key: key);
#override
_PresentChipState createState() => _PresentChipState();
}
class _PresentChipState extends State<PresentChip> {
var isSelected = false;
var c = false;
#override
Widget build(BuildContext context) {
final SelectSub selectSub = Provider.of<SelectSub>(context);
final Date date = Provider.of<Date>(context);
db.checkAtt(widget.candidate, selectSub.selectsub, date.datenew).then((result){
print(result);
setState(() {
c = result;
});
});
return Container(
child: ChoiceChip(
label: Text('Present'),
selected: isSelected,
onSelected: (selected) {
db.gibAtt(
widget.candidate, selectSub.selectsub, date.datenew.toString());
setState(() {
isSelected = selected;
});
},
backgroundColor: !c ?Colors.red :Colors.green ,
selectedColor: !c ?Colors.red :Colors.green ,
));
}
}

Answer 1

Assuming you only want to read once from firestore, you need a FutureBuilder.
return Container(
child: FutureBuilder(
future: db.checkAtt(widget.candidate, selectSub.selectsub, date.datenew),
builder: (context, snapshot) {
if(snapshot.hasData)
return ChoiceChip(
...
backgroundColor: !snapshot.data ?Colors.red :Colors.green,
selectedColor: !snapshot.data ?Colors.red :Colors.green,
);
//Return another widget if the future has no data
return Text('Future has no data');
}
)
);
If you need your UI to react to changes from firestore, use a StreamBuilder.
You can remove the following bloc from your build method:
db.checkAtt(widget.candidate, selectSub.selectsub, date.datenew).then((result){
print(result);
setState(() {
c = result;
});
});